Short-term impacts of winter bale grazing beef cows on forage production and soil nutrient status in the eastern Canadian prairies

The impact of winter bale grazing on forage productivity and nutrient cycling was determined near Winnipeg, MB. Variable distribution of nutrients and forage yield within bale grazed plots on a perennial grass-legume forage field was identified using an intensive grid sampling method. In bale-grazed plots, mean dry matter (DM) yield of forage decreased 68% in year one following bale grazing, with no difference in DM yield in year two following bale grazing, relative to an untreated control. Decreased yield was attributed to the large mass of waste feed and feces (21% of feed delivered) that remained at the centre of each bale-grazed plot, where each bale was placed. Concentrations of crude protein, total digestible nutrients, phosphorus (P), and potassium in forage increased in the first growing season following winter bale grazing compared to the control, particularly at the centre of each bale-grazed plot. Concentrations of residual nitrate-nitrogen and Olsen P in soil were 15 and 2.5 times greater, respectively, at the centre of the bale-grazed plots compared to untreated control plots. Dispersion of waste feed packs when bale grazing in sub-humid climates on clay soils is recommended to minimize smothering and encourage rapid decomposition of waste feed and feces. Long-term studies are needed to determine the potential benefits and risks of bale grazing to forage productivity and soil nutrient status in the eastern Canadian prairies.